How was this done????

It's a pretty neat video with some cool effects, but my main focus is at the :05 second mark. Here we see the current UFC light heavyweight champion, Jon Jones, shadow boxing in a white room, IN FRONT OF large black text that says "January 22".

I was just wondering how someone would go about doing this? I hope I'm not just thinking to hard and missing something easy...but it just sort of boggled me how he was able to embed the text perfectly behind Jon Jones. Do you have to set Jon Jones as some kind of 'layer' in post, and then put the text behind it? Are there any special filming techniques that he could've used to create this?

Any help would be greatly appreciated, look forward to hearing from you guys!

There are a couple of possibilities - one, it was done with the fighter on a greenscreen - two, the clip with the fighter on it was duplicated, then the roto brush was used to remove him from the background (for the front layer copy), enabling the text to be put in between the layers.

My guess would be greenscreen, since the wall background just doesn't look real to me.